#include "bucketsort.h"

extern void bucket_sort_intersect(uint32_t* const estart, uint32_t* const estop,
								  uint32_t* const ostart, uint32_t* const ostop,
								  bucket_info_t *bucket_info, bucket_array_t bucket)
{
	uint32_t *p1, *p2;
	uint32_t *start[2];
	uint32_t *stop[2];

	start[0] = estart;
	stop[0] = estop;
	start[1] = ostart;
	stop[1] = ostop;

	// init buckets to be empty
	for (uint32_t i = 0; i < 2; i++) {
		for (uint32_t j = 0x00; j <= 0xff; j++) {
			bucket[i][j].bp = bucket[i][j].head;
		}
	}

	// sort the lists into the buckets based on the MSB (contribution bits)
	for (uint32_t i = 0; i < 2; i++) {
		for (p1 = start[i]; p1 <= stop[i]; p1++) {
			uint32_t bucket_index = (*p1 & 0xff000000) >> 24;
			*(bucket[i][bucket_index].bp++) = *p1;
		}
	}

	// write back intersecting buckets as sorted list.
	// fill in bucket_info with head and tail of the bucket contents in the list and number of non-empty buckets.
	uint32_t nonempty_bucket;
	for (uint32_t i = 0; i < 2; i++) {
		p1 = start[i];
		nonempty_bucket = 0;
		for (uint32_t j = 0x00; j <= 0xff; j++) {
			if (bucket[0][j].bp != bucket[0][j].head && bucket[1][j].bp != bucket[1][j].head) { // non-empty intersecting buckets only
				bucket_info->bucket_info[i][nonempty_bucket].head = p1;
				for (p2 = bucket[i][j].head; p2 < bucket[i][j].bp; *p1++ = *p2++);
				bucket_info->bucket_info[i][nonempty_bucket].tail = p1 - 1;
				nonempty_bucket++;
			}
		}
		bucket_info->numbuckets = nonempty_bucket;
	}
}
